@JackMurdoc If there is going to be improvement with G/C, it would take awhile. One of mine had the popping noise, I thought it was the hip, it turned out to be a knee.
I started the G/C, and within about a few months, the popping was gone. The dog was much younger than yours,though, when I started with it. You might check his knee caps-it could be subluxating.